clear;
data1 = load('B1.txt');
x1 =data1(:,1);
y1 = data1(:,2);
data2 = load('B2.txt');
x2 =data2(:,1);
y2 = data2(:,2);
data3 = load('B3.txt');
x3 =data3(:,1);
y3 = data3(:,2);
data4 = load('B4.txt');
x4 =data4(:,1);
y4 = data4(:,2);
plot(x1,y1,'r')
hold on
plot(x2,y2,'g')
plot(x3,y3,'b')
plot(x4,y4,'c')
x=-5:0.1:5;
for i=1:101
    y(i) = 1/(1+x(i)*x(i));
end
plot(x,y,'k')
legend('n=2','n=4','n=6','n=8','f')
